KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF AGRICULTURE AND NATURAL RESOURCES FACULTY OF AGRICULTURE DEPARTMENT OF HORTICULTURE Investigation into fungal seedborne pathogens of farmer-saved seed maize (Zea mays L.) collected from three ecological zones of Ghana and efficacy of plant extracts in controlling the pathogens Joseph Adjei February, 2011 Investigation into fungal seedborne pathogens of farmer-saved seed maize (Zea mays L.) collected from three ecological zones of Ghana and efficacy of plant extracts in controlling the pathogens A THESIS SUBMITTED TO THE SCHOOL OF POST GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE DEGREE IN SEED SCIENCE AND TECHNOLOGY AT THE DEPARTMENT OF HORTICULTURE OF THE FACULTY OF AGRICULTURE, COLLEGE OF AGRICULTURE AND NATURAL RESOURCES, KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY, KUMASI, GHANA JOSEPH ADJEI FEBRUARY, 2011 CERTIFICATION I hereby declare that this submission is my own work towards the MSc (Seed Science and Technology) degree and that, to the best of my knowledge, it contains no material previously published by another person nor material which has been accepted for the award of any other degree of the University, except where due acknowledgment has been made in the text. Adjei Joseph ...................................... .................................... Student Signature Date Certified by: Prof. (Mrs) N. S. Olympio ..................................... .................................... Supervisor Signature Date Dr. E. Moses ...................................... ..................................... Co-supervisor Signature Date Dr. B. K. Maalekuu ....................................... ..................................... Head of Department Signature Date ii ABSTRACT Seedborne fungal pathogenic infections of maize (Zea mays L.) were studied using fifty-four (54) seed samples, collected from locations in the Forest, Transitional and Guinea Savannah ecological zones in Ghana. The deep-freeze blotter method was used to detect fungal pathogens on the seed maize. Four pathogens identified were Acremonium strictum (infection ranging from 0.5 to 22%), Bipolaris maydis (0.5 to 1.5%), Botryodiplodia theobromae (1 to 19%) and Fusarium moniliforme (5 to 84.5%). Aqueous extracts of Cymbopogon citratus (lemongrass), Chromolaena odorata (siam weed) leaf and Azadirachta indica (neem) seeds were tested for their inhibitory activity against seedborne fungal pathogens in the infected seed maize, using 50% (w/v) concentrations for 1, 3, 6 and 24 hours each. Neem seed extract exhibited the best control, reducing infection of F. moniliforme from 68 to 18% with the 24 hours of treatment and eliminating Acremonium strictum at 1 and 24 hours of treatment. Botryodiplodia theobromae infection was eliminated at all the soaking periods. Neem had no effect on germination but reduced vigour slightly. Chromolaena odorata leaf extract also exhibited control on F. moniliforme reducing infection from 68 to 36.5% at 24 hours of treatment but had no significant effect on germination and vigour of seeds. Lemongrass extract did not have significant control effect on F. moniliforme but increased germination and vigour of seeds. There is therefore a potential of using neem seed extract as seed maize disinfectant against F. moniliforme, Acremonium strictum and Botryodiplodia theobromae. iii ACKNOWLEDGEMENT I wish to express my sincere appreciation to my supervisor, Dr. (Mrs) N. S. Olympio, of the Department of Horticulture, Faculty of Agriculture, Kwame Nkrumah University of Science and Technology, whose advice, suggestions, patience and objective criticism guided me throughout the period of the project work. I am very grateful for her invaluable assistance especially her motherly advice and care that propelled me through the work successfully. In a similar manner I extend my heartfelt gratitude to my co-supervisor, Dr. E. Moses, of Crop Research Institute (CRI), Fumesua, Kumasi for his advice, suggestions and guidance during the laboratory work and writing of the thesis. I must thank the Head, Dr. B. K. Maalekuu and all the lecturers of the Department of Horticulture whose constructive criticism during seminar presentations finally straightened up the research. I owe a word of special thanks to my course-mate, Mr. David Sackey, for his immense assistance in providing blotter papers and other materials without which the work would not have been possible. I also thank Dr. Robert Asuboah of Grains and Legumes Development Board, Kumasi, for making their seed laboratory accessible to me to carry out the germination and vigour tests. I express my sincere appreciation to the staff of Seed Pathology laboratory, CRI, Fumesua – Mr. Samuel Nyarko, Mrs Zippora Appiah-Kubi, Ms Rose Barfi, Madam Comfort Nkrumah, Mrs Esther Dwirah and the National Service Personnels for their assistance. Above all, I thank Almighty God who gave me strength and protection to carry out the research. iv TABLE OF CONTENTS CERTIFICATION ................................................................................................... ii ABSTRACT ........................................................................................................... iii ACKNOWLEDGEMENT ...................................................................................... iv LIST OF TABLES ................................................................................................ viii LIST OF FIGURES ................................................................................................ ix LIST OF APPENDICES .......................................................................................... x LIST OF ACRONYMS .......................................................................................... xi 1.0 INTRODUCTION .......................................................................................... 1 2.0 LITERATURE REVIEW................................................................................ 4 2.1 Origin and Botany of Maize............................................................................ 4 2.2 Importance of Maize ....................................................................................... 5 2.3 Maize Production Trends ................................................................................ 6 2.4 Maize production constraints .......................................................................... 7 2.5 Diseases of Maize ........................................................................................... 7 2.5.1 Major Fungal Diseases of Maize .............................................................. 8 2.5.2 Downy mildews ....................................................................................... 8 2.5.3 Black Bundle Disease and Late Wilt ........................................................ 9 2.5.4 Anthracnose Stalk Rot .............................................................................. 9 2.5.5 Southern leaf blight .................................................................................10 2.5.6 Charcoal Stalk Rot ..................................................................................10 2.5.7 Horse’s tooth ...........................................................................................11 2.5.8 Aspergillus Ear Rots ...............................................................................11 2.5.9 Gray Ear Rot ...........................................................................................11 2.5.10 Common Smut ......................................................................................12 v 2.5.11 Botryodiplodia or Black Kernel Rot ......................................................12 2.5.12 Fusarium Stalk Rot ................................................................................12 2.5.13 Fusarium Ear Rot ..................................................................................13 2.6 Effect of Seedborne Fungal Diseases on Man and Animal .............................14 2.7 Control of Seedborne Diseases ......................................................................15 2.7.1 Types of Seed Treatment .........................................................................15 2.7.2 Physical ..................................................................................................15 2.7.3 Biological Control Agents .......................................................................17 2.7.4 Chemical method (Use of Fungicides) .....................................................18 2.7.5 Effects of Chemical Seed Treatments ......................................................19 2.7.6 Plant or Botanical Extracts with Fungicidal Properties ............................20 2.7.7 Effect of Neem on Fungi .........................................................................21 2.7.8 Effect of Lemongrass (Cymbopogon citratus) on Fungi ...........................22 2.7.9 Chromolaena odorata .............................................................................22 2.7.10 Mancozeb (Chemical fungicide) ............................................................23 3.0 MATERIALS AND METHODS ...................................................................24 3.1 Seed Samples ................................................................................................24 3.2 Seed Health Analysis .....................................................................................25 3.2.1 Plating